Physical correlates of prosodic structure in American Sign Language

Abstract

1 Introduction The study of ASL prosody provides insights into the specification of stress, rhythmic structure, and intonation in conjunction with the syntax of a natural signed language. It allows us to test claims about the language-and modality-independence of various prosodic phenomena. Intonation in speech, for example, is dependent on pitch, which is not available in the manual modality. Stress marking in speech depends on pitch, duration, and amplitude. Rhythmic phrasing in speech, by which a beat pattern is established and varied for purposes of linguistic grouping, involves duration and pausing. By comparison of the intonation and rhythm mechanisms in ASL with those in spoken languages, we are able to separate the functions of intonation and rhythm in language from their expression in different languages and modalities. There is evidence that over time, ASL has accommodated to the production and perception requirements of the manual/visual modality, resulting in a prosodic system that is comparable in function to spoken languages but different in means of expression. Detailed investigation of perception and production of spoken languages has provided a reasonably clear picture of the relative roles of duration, frequency, amplitude, tempo, and pausing in prosodic structure. In contrast, the prosodic structure of sign languages has not attracted much attention even though it represents a fundamental investigation if our aim is to fully understand how language works. One problem is the difference in physics/kinematics. The variables available for use in signing are displacement (how far the articulator travels), duration, velocity (how much displacement in a unit of time), acceleration (changes in velocity per unit time), and jerk (changes in acceleration per unit time). Existing speech research methods and equipment are not designed to handle these variables. The technological problems are also formidable, comparable to research on speech before the invention of tape recording. However, the linguistic problems are even more daunting, comparable to research on speech before the development of alphabets, not just the IPA. Thus, we begin with old-fashioned 'primitive' measures, namely signers' judgments of input stimuli.